It is conventionally known that, by putting two displays in alignment and using the two displays as one display, it is possible to increase a size of a display of a portable terminal (Patent Literature 1).
As a method of displaying an image, etc., there exists conventional technology that changes an orientation of an image to be displayed according to an orientation of a display, i.e. whether a long side of the display is vertical or horizontal. According to this technology, by detecting whether the long side or a short side of the display is vertical or horizontal, the orientation of the display can be known, and according to the orientation of the display, it is possible to switch between a portrait display mode where a long side of an image to be displayed is orientated vertically and a landscape display mode where a long side of an image to be displayed is orientated horizontally.